Scientists have discovered that ordinary ice is a flexoelectric material, capable of generating electricity when bent or unevenly deformed.
"Frozen water is one of the most abundant substances on Earth. It is found in glaciers, on mountain peaks and in polar ice caps. Although it is a well-known material, studying its properties continues to yield fascinating results.
An international study involving ICN2, at the UAB campus, Xi'an Jiaotong University (Xi'an) and Stony Brook University (New York), has shown for the first time that ordinary ice is a flexoelectric material. In other words, it can generate electricity when subjected to mechanical deformation. This discovery could have significant implications for the development of future technological devices and help to explain natural phenomena such as the formation of lightning in thunderstorms.
The study, published in the journal Nature Physics, represents a significant step forward in our understanding of the electromechanical properties of ice. "We discovered that ice generates electric charge in response to mechanical stress at all temperatures. In addition, we identified a thin 'ferroelectric' layer at the surface at temperatures below -113ºC (160K). This means that the ice surface can develop a natural electric polarization, which can be reversed when an external electric field is applied -- similar to how the poles of a magnet can be flipped. The surface ferroelectricity is a cool discovery in its own right, as it means that ice may have not just one way to generate electricity but two: ferroelectricity at very low temperatures, and flexoelectricity at higher temperatures all the way to 0 °C " explains Dr Xin Wen, a member of the ICN2 Oxide Nanophysics Group and one of the study's lead researchers. This property places ice on a par with electroceramic materials such as titanium dioxide, which are currently used in advanced technologies like sensors and capacitors.
One of the most surprising aspects of this discovery is its connection to nature. The results of the study suggest that the flexoelectricity of ice could play a role in the electrification of clouds during thunderstorms, and therefore in the origin of lightning."
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